1. Field of the Invention
The present invention generally relates to methods and systems for designing multilevel halftone screens. More particularly, the present invention relates to methods and systems for designing multilevel halftone screens using spot functions.
2. Description of the Related Art
Halftoning is the process of converting a continuous tone image to an image with reduced bit depth having the appearance of being a continuous tone image when viewed from a distance. This process is necessary to appropriately render images on printers or other display devices. The vast majority of printers in use today are binary printers. Many display devices are capable of displaying information using multiple intensity levels. Printers increasingly are being developed which have the ability to print more than two levels of intensity for a given ink or toner. These are known as multi-level printers. Additional printer levels can dramatically improve the quality of printed images.
There are many conventional ways in which one can take advantage of the ability to print multi-levels. However, many of these methods will not show satisfactory results on electro-graphic printers due to the complex toner and electrical charge considerations involved in the printing process of these devices. Therefore, in practice, the final result of conventional halftoning with multi-levels is often not significantly better on these types of printers when compared with binary printers.